In a conventional mobile network, when user equipment (UE) is out of network coverage (for example, an emergency such as an earthquake occurs), UE that is in network coverage may be used as a relay such that the UE that is out of network coverage can communicate with a network side.
For ease of understanding, referring to FIG. 1A, FIG. 1A is a schematic diagram of a network architecture. In the schematic diagram, remote UE is UE that is out of network coverage (for ease of description, the UE that is out of network coverage is referred to as a remote terminal), and relay UE is UE that is in network coverage (for ease of description, the UE that is in network coverage is referred to as a relay terminal). The relay terminal may simultaneously serve as a relay for multiple remote terminals. In an existing method, when multiple remote terminals need to request to obtain a same piece of group data from a server, each remote terminal needs to establish a unicast communication connection to the server, where the unicast communication connection is used to request and receive the group data. The server sends the requested group data to each remote terminal based on the unicast communication connection. When information is being exchanged between the server and the remote terminal, because the information needs to be forwarded using a relay terminal, the same group data is repeatedly transmitted over a Uu interface, thereby undoubtedly reducing data transmission efficiency.